The purpose of the invention is to propose a new type of electrical energy power supply of an electrical resistive heating element with processed signal enabling in particular an improvement in the heating conditions by means of the Joule Effect of the resistive element and a very great reduction in the weight of generator type equipment fitted with a corresponding power supply circuit.
The invention is particularly applied, in the gas field and in the distribution of water or the flow of waste water, for the electrical energy supply of accessories generally denoted by the term "electro-weldable", principally intended for the construction or repair of pipe systems made from plastic material, such as high density polyethylene (density usually between 920 and 950 kg/m.sup.3) or for example made from polypropylene. Still in the same field, the invention could be used for the supply of electro-heating accessories, particularly heat-shrink accessories, for the repair of cast iron or steel pipes, or for ensuring their heterogeneous assembly (different materials).
Another possible application of the invention could relate to the field of industrial electricity and in particular to the supply of thermo-mouldable accessories for the protection, repair or maintenance of electrical cables or of telecommunications networks.
Various systems of course already exist on the market for supplying a resistive heating element with the desired electrical energy.
Known systems operate for supplying, from a 110 or 220 volt a.c. source, a voltage which is usually a reduced voltage in a range of approximately 12 to 48-50 volts, by means of an electromagnetic induction transformer, or even an auto-transformer.
Such supply systems must be able to be used on the ground, the a.c. sources are usually constituted on the basis of a worksite generator or a so-called "portable" generating set, capable of supplying in the order of 2 to 4 kwatts and having a weight usually in the order of 20 to 25 kg, i.e. heavy and bulky in fact.
Another disadvantage of the known systems is that they re-inject current harmonics into the mains used for supplying the resistive element. And the voltage harmonic interference which can also appear can even lead to significant downgrading of the generator between the nominal power and the actually usable power.